SLIDE 1
MS4
2 MS4
Applying LID in MS4 permits
- Regulatory environment
- Arizona’s Municipal Separate Storm
Sewer System (MS4) Permit
- Low Impact Development Practices
- Areas of benefit and limitation
- Next steps
Applying LID Practices in Arizonas MS4 permit Marie Light LID - - PowerPoint PPT Presentation
Applying LID Practices in Arizonas MS4 permit Marie Light LID - - PowerPoint PPT Presentation
MS4 Applying LID Practices in Arizonas MS4 permit Marie Light LID Workshop Pima County Regional Flood Control District March 15, 2011 8:00a 4:00p Tucson, AZ MS4 Applying LID in MS4 permits Regulatory environment Arizonas
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SLIDE 3
3 MS4
Protecting the Nation’s Waters
Constitution of United States Preamble Article 1 Article 6 Clean Water Act Pollution Prevention
- Non-point Sources
- Point Sources
Arizona Pollutant Discharge Elimination System
AZPDES Construction AZPDES Industrial AZPDES MS4
Stormwater point sources
NPDES MS4
SLIDE 4
4 MS4
Portion of Hydrologic Cycle Regulated by MS4
Cloud Formation
SLIDE 5
5 MS4
Layout of an AZPDES MS4
Inflow
- Pipe ID > 12”
- Area > 2 acres
Outflow
- Pipe ID > 36”
- Area > 50 acres
- Catchment land use
is industrial Municipal Separate Storm Sewer System
- System owned by State, County, or
City that discharges to waters of the US
- Collects or convey storm water
- utfall
- utfall
SLIDE 6
6 MS4
Contents of an AZPDES MS4
Practices to prevent runoff from washing pollutants into local surface waters 1. Define control measures in Stormwater Pollution Prevention Plan (SWPPP) 2. Implement control measures
- Education and training
- Inspect: Outfalls, Construction sites & Industrial facilities
- Survey illicit discharges
- Monitor Water quality monitoring
- Post-construction
3. Evaluate control measures
- 4. Modify SWPPP
- 5. Report Annual Results
- u
t f a l l
- utfall
SWPP
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7 MS4
Strong support for LID
- 1. Federal level
– Watershed approach – Sustainability programs
- 2. State level (requirement in MS4)
– Evaluate how LID can reduce pollutants
- New construction
- Redevelopments
- Retro-fits of commercial and residential areas
- 3. Local level
SLIDE 8
8 MS4
Principles of LID related to water
- Reduce volume of runoff:
– Simulating natural runoff (& infiltration) – Reducing peak flows during storm events – Watering the ecosystem
- Improve surface water quality by:
– Using natural chemical processes – Using natural biological processes
NRDC, 2001
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9 MS4
How LID benefits storm water management
↑Interception ↓runoff ↑Evaporation ↓runoff ↑Infiltration ↓runoff ↑Sediment Removal ↑Filtration ↑Energy dissipation ↓Runoff ↑Water quality ↑Transpiration ↓runoff ↑Soil rxn ↑water quality ↑nutrient recycling ↑water quality ↑microbial decomposition ↑ water quality
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10 MS4
City of Tucson, 2005
LID Reduces Runoff Coefficient
0 20 40 60 80 100 Percent Imperviousness 100 year flood event 100 year flood event 5 year flood event 5 year flood event 2 year flood event 2 year flood event Greatest benefit at Short return intervals
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11 MS4
Areas Likely to see Benefits in MS4
- Roads with right-of-way available for LID
- Parking lots
- Roofs
- Landscaped areas
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12 MS4
Trees Wildflowers Grasses Shrubs Groundcovers Cacti Accumulation ⇒ O&M
- sediments
- heavy metals
Watershed Management Group, 2010 Higher costs
- Design/construct
- O&M
- plant care
- cleanout sediments
Agaves, yuccas
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13 MS4
Next steps
1. Research urban system
- soil chemistry in energy dissipation areas
- Water chemistry of storm water for land uses
- Residential
- Commercial
- Industrial
2. Refine designs 3. Refine plan review process for new features/functions 4. Develop cost comparisons for LID in arid environments
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14 MS4
Summary
1. LID endorsed at federal level 2. Evaluation of LID is required in Arizona’s MS4 3. High capacity to improve
- Flood control
- Surface water quality
4. Next steps
- Research
- Refine designs and plan reviews
- Develop support infrastructure
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15 MS4